1. Field of the Invention
The present invention relates generally to an apparatus and a method for an Automatic Retransmission reQuest (ARQ) in a wireless communication system. More particularly, the present invention relates to an apparatus and a method for an asynchronous ARQ in a multihop relay wireless communication system.
2. Description of the Related Art
In a wireless communication system, particular data may suffer error depending on a channel state of a radio resource that delivers the data. Error controlling and recovering schemes largely include an Automatic Retransmission reQuest (ARQ) scheme and a Forward Error Correction (FEC) scheme. The ARQ scheme requests a transmitter to retransmit the corrupted data of a receiver. The FEC scheme corrects the error of the compromised data of the receiver.
When the wireless communication system adopts the ARQ scheme, the receiver determines whether an error occurs by decoding the received packets. When the received packets are free from error, the receiver sends an Acknowledgement (ACK) signal to the transmitter.
When errors are detected in the received packets, the receiver sends a Negative ACK (NACK) signal to the transmitter.
Upon receiving the ACK message from the receiver, the transmitter transmits new packets. By contrast, when receiving the NACK message from the receiver, the transmitter retransmits the previous packets to the receiver.
Recently, the wireless communication system has adopted a relay scheme using a relay station to provide a better radio channel to a mobile station that travels in a cell boundary or in a shadow area, i.e., the wireless relay communication system can provide a better radio channel between a base station and a mobile station by relaying data between the base station and the mobile station using the relay station.
In order to provide a better radio channel as described above, the wireless relay communication system requires an ARQ method that uses the relay station.